Agents / Standard term
Agent skill
A reusable instruction package for a defined task, typically with routing metadata and optional references, scripts, templates, examples, or assets.
An agent Skill gives a workflow a maintained package instead of leaving its procedure inside one chat. In Codex, a filesystem-backed Skill uses a folder with a SKILL.md entrypoint and may include supporting resources. Claude products also expose Skills, while their installation, packaging, and discovery rules vary by surface. A Skill can load through explicit selection or automatic routing when the product and metadata support it. The package supplies context; it does not guarantee that the agent follows it or that the procedure is current.
Builder example
Skills reduce repeated setup and let teams version procedures, examples, and checks. Portability depends on referenced tools, file conventions, product features, and permissions. A well-routed Skill can still produce bad results when its evidence or tests are stale.
Common confusion: A prompt requests one run, durable instructions set broad defaults, and a Skill packages a task-specific procedure. The boundaries differ by product, so check the active runtime rather than assuming one loading model everywhere.